Acquia Dev Desktop is currently compatible with MacOS 10.15 Catalina. Make sure the software is updated to the latest version and visit our release notes for more information.
For previous versions of the app, on previous versions of MacOS (that is, previous to Catalina), you might see an alert with this text:
This app will not work with future versions of macOS and needs to be updated to improve compatibility. Contact the developer for more information.
Acquia is the developer of Dev Desktop, and as stated above, update Dev Desktop to the latest version and that alert should no longer show.
Be aware that support for Dev Desktop is ending shortly. You can still use the application but Acquia Support will no longer provide assistance on the product. See this for further details on when that support ends.